Using Captured CO2 for Artificial Photosynthesis
Funded through the Biological Greenhouse Gas (GHG) Management program in 2014, this project developed a non-living system that mimics photosynthesis to convert industrial carbon emissions into valuable chemicals. The project aimed to demonstrate a scalable, modular technology for carbon capture and utilization.
This technology uses captured industrial CO2, light, water and engineered enzymes to produce chemicals that can be used in Alberta’s petrochemical infrastructure. The process uses a series of large tanks called bioreactors to replicate the second stage of photosynthesis, which turns carbon dioxide from the air into the food plants need to grow.
Overall, carbon capture biotechnologies reduce industrial greenhouse gas emissions by capturing CO2 and converting it into valuable, marketable chemicals. This artificial photosynthesis was created to address the limitations of the living cells typically used in carbon capture biotechnologies. Living organisms require large amounts of energy and nutrients to help grow and repair their cells. Producing chemicals from living organisms also uses a lot of additional energy and steps to turn them into products. In contrast, artificial photosynthesis does not require extra energy and nutrients to repair or grow cells and can directly produce specific chemicals without extra refining processes. This reduction in energy consumption results in a more efficient process, thereby reducing emissions.
Engineering Enzymes from E. Coli
The project demonstrated proof of concept, and the individual components for artificial photosynthesis were successfully developed. The project faced several major challenges along the way; however, starting with the high cost and limited availability of enzymes needed for the artificial photosynthesis system. To solve this, the team developed their own enzyme production process using genetically engineered E. coli, giving them more control over supply and cost. Another key challenge was restricting the enzyme’s movements, which is necessary for creating a stable, reusable system. The best method they tested significantly reduced enzyme efficiency, showing that better immobilization strategies are still needed.
Additionally, bringing all parts of the systems together, including the CO2 capture, enzyme reactions, and the bioreactors, added complexity and required careful coordination to keep everything running smoothly. Scaling the system to real-world levels also introduced further technical and economic hurdles that must be addressed before commercial use.
What’s next?
This project was completed in 2016, and through this work, the team gained valuable insights like the value of in-house enzyme production and the benefits of a modular system design that lets different parts be tested and improved separately. While they were able to prove the concept works, the technology still needs improvements in efficiency, durability, and engineering in order to scale up further.